You Can Hear Me Now, But What About Tomorrow?

For a full generation now, DSP — digital signal processing — has revolutionized audio. From the advent of digital audio recording in the 1970's, to the Compact Cisc, then the DVD and Blu-ray discs, and MP3, Napster, and the iPod revolution, DSP has been the dilithium crystal at the core. You could even argue that without DSP and its perceptual coding of the MP3 (and MP4/AAC) formats, there'd have been no iPod and thus, probably, no iPhone, and therefore possibly no smartphones at all. And how different a place would the world be today?

So any way you slice it, DSP is important. And now, beyond merely making a few folks a great deal of money and enabling the rest of us to listen to Justin Bieber and watch cat videos, it's poised to perform some magic that may actually benefit humanity, in the world of hearing assistance.

If you're white, male, and middle-aged, should you live long enough, two things are certain. One is that you will eventually develop prostate cancer; the other is that you will to one degree or another lose your hearing. These are conditions that evolution, necessarily focused around the breeding years, just has not had millennia enough to select out. (For example, it doesn't matter if you can't read a wine list once you're no longer able to overpower other males and select a mate: hence presbyopia or farsightedness.)

DSP can't do much about the first — don't worry, it's a slow grower, and something else will probably kill you first — but it may hold real promise for the second. Of course, DSP has been used in the newer generations of hearing aids for at least a decade, but I know from experience that even the best — or at least, most expensive — of these "smart" digital filters are only crude processors at best.

My dad, who died late last year at 95, lost most of his hearing over the last decade of life, and despite retaining every one of his marbles till almost the very end, it was a sad, isolating, and ultimately defeating struggle. I helped him with his hearing aids all along, and despite endless hearing tests, trials, re-programmings, and adjustments, their efficacy was never very high. I know, because I tried them all. One-on-one in a very quiet room he was pretty good; anything else was mostly hopeless, which has been the complaint of hearing-aid users from time immemorial. Beethoven's ear-trumpet was one solution; shouting is another, but neither is terribly practical nor desirable in modern life.

Fortunately, modern technology may be on the trail of a solution, thanks to — you guessed it — DSP. Plus, neural networks, "deep-learning" machine-learning algorithms, and the nano-ization of processing hardware and transducers. A recent article from IEE Spectrum (the journal of the Institute of Electrical and Electronics Engineers) recounts research conducted at Ohio State University, building on work at McGill and elsewhere, to develop "actively smart" (my words) DSP filtering that can extract speech from blanketing noise, including other voices — the long-known "cocktail-party effect" — with astonishing precision.

It's a fascinating read, and features links to technical papers for the geeks among us, and best of all a handful of before-and-after audio samples for the rest of us. One of the most interesting points, to me at least, was that these suppress the residual background noise into precisely the same sort of warbly, watery residue that's buried in the "grass" of every MP3 file. (You can hear an example in the stereo-difference component of a typical stereo MP3: simply play a track in plain-vanilla Dolby Surround, while disconnecting the front speakers; the surrounds will present, more or less, the L-R-plus-R-L component, "naked," and these residuals should be easily audible.)

Of course, these lab examples undoubtedly ran on desktop workstations, but given recent experience, how long can it be before the same functions can be delivered by the average smartphone? A few years, no more.

All this gives me hope. Apple is said to be working on this kind of thing, which makes perfect sense: we are, after all, their market demographic, and with the U.S. hearing-aid market at $6 billion per annum and growing apace the dollars are there. No doubt the big hearing-aid firms are running the same trail. I figure I've got at least a decade's worth of good hearing left, hopefully two, and maybe a few years more. After that, I'm pinning my hopes on DSP.

okie's picture

Daniel - the Kumin Factor was written in March; it's almost July, too short a metric to use in judging hearing-aid industry progress. You certainly offer some valid points of potential progress.
But my direct experience and testing (three different places)in the past six months... very little if anything has changed. $6,000 to $8,000 "aids" that are grossly overpriced - and do very little per se. Items that likely cost only a few hundred dollars to manufacture.
Inevitably the advisement "you'll have to wear these and get used to them, 30, 60 days, maybe months!"
I've encountered no success with the products. Key issue appears to be "fitment" and "adjustment" skills by the audiologists, even doctors of audiology. Years of learning and degrees accumulated, but apparently only a brief class taken on how to fit and adjust.
Astonished to realize none can test and validate the sound output at ear-drum level.... to determine if it matches adjustments applied to the aids' computer chip.
Office evaluation is always "how do things sound?" and the customer is supposed to describe in allegedly detailed audio terms what is, or isn't right. Absurd! Thereafter, another guess is applied to the chip's adjustment... "give 'em a try for a few weeks or a month..."
Trial & Error at the lowest level. $6,000 to $8,000 devices!

Another aspect I never could grasp: if hearing aids require weeks and months "of getting used to, for our brains to adapt"... why is it that the same doesn't apply when we get new audio speakers, or slip on headphones? The clarity difference with the latter, decent $300 headphones, far surpasses hearing quality with allegedly custom-tuned $6,000 hearing aids. Yet I don't have to wear headphones for a month or two to hear better. The enjoyment is immediate.